This invention relates generally to gas turbine engines, and more specifically to methods and apparatus for assembling gas turbine engines.
At least one known gas turbine engine includes, in serial flow arrangement, a forward fan assembly, an aft fan assembly, a high-pressure compressor for compressing air flowing through the engine, a combustor for mixing fuel with the compressed air such that the mixture may be ignited, and a high pressure turbine. The high-pressure compressor, combustor and high-pressure turbine are sometimes collectively referred to as the core engine. In operation, the core engine generates combustion gases which are discharged downstream to a low pressure turbine that extracts energy therefrom for powering the forward and aft fan assemblies. Within at least some known gas turbine engines, at least one turbine rotates in an opposite direction than the other rotating components within the engine.
At least one known gas turbine engine includes a mid turbine frame to support the high pressure turbine, at least one intermediate pressure turbine, and a turbine rear frame to support a second low pressure turbine. During engine assembly, such known gas turbines are assembled such that the high pressure turbine is coupled forward of the turbine mid frame and the at least one intermediate pressure turbine is coupled aft of the turbine mid frame.
Accordingly, to provide the necessary structural strength to the engine, within such engines, the turbine mid frame structurally supports the high pressure turbine and the intermediate turbine. During operation, the cycle temperatures within the gas turbine engine generate an increased temperature at the turbine mid-frame. As such, additional cooling is supplied to the turbine mid-frame to facilitate reducing an operating temperature of the turbine mid-frame.